HR: 1340h
AN: B33D-1595    [Abstracts]
TI: The Effect of Increased CO2 Mixing Ratio on Water Use Efficiency, Evapo-transpiration, Soil Moisture Content and Stem Flow in two Long-term Field Experiments
AU: * Drake, B
EM: drakeb@si.edu
AF: Smithsonian Environmental Research Center, PO Box 28, Edgewater, MD 21037, United States
AU: Powell, T
EM: Powellt@si.edu
AF: Smithsonian Environmental Research Center, PO Box 28, Edgewater, MD 21037, United States
AU: Li, J
EM: Lij@si.edu
AF: Smithsonian Environmental Research Center, PO Box 28, Edgewater, MD 21037, United States
AU: Hinkle, R
EM: rhinkle@mial.ucf.edu
AF: Biology Department, University of Central Florida, Orlando, FL 32816, United States
AU: Rasse, D
EM: daniel.rasse@bioforsk.no
AF: BIOFORSK, Frederick A Dahls Vei 20, As, 1432, Norway
AB: Stomatal opening in plant leaves control carbon and water exchange between vegetation and the atmosphere. Closure of these water-gates in response to increased atmospheric CO2 mixing ratio's, reduces transpiration under most laboratory and short term experimental conditions. Does this imply however, as atmospheric CO2 rises, and plant canopies expand, that evapo-transpiration (ETR), soil moisture content (SMC), and ecosystem water use efficiency (WUE) will increase? To test this question, field experiments have been and still are conducted using open top chambers. We have exposed native species in Florida Scrub to a carbon dioxide mixing ratio of nearly 700 ppmv CO2 for the past ten years and in Chesapeake Bay wetlands for 21 years. As a result of this treatment, in both ecosystems there was an increase in net ecosystem CO2 exchange and leaf area but a reduction of stomatal conductance, stem flow, transpiration, and ETR. For Florida scrub oak, these changes were also accompanied by an increase in soil moisture content as well.
DE: 0410 Biodiversity
DE: 0428 Carbon cycling (4806)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0495 Water/energy interactions (1878)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting